A conventional air conditioning apparatus indoor unit adapted for ceiling mounting typically includes a casing for housing a fan and a heat exchanger, a square-shaped air suction inlet formed centrally in the underpart of the casing and straight groove-like air discharge outlets formed so as to extend, around the air suction inlet, along four sides of the air suction inlet, respectively. In the indoor unit, indoor air drawn in through the air suction inlet when the fan is driven is heated or cooled to generate conditioned air, and the conditioned air is discharged in four directions through the air discharge outlets, respectively.
Generally, such an air discharge outlet is provided with a flap (vane) capable of vertical adjustment with respect to the flow direction of air discharged therefrom. The flap is mounted such that it can be swung about a longitudinal axis of the air suction inlet.
And now, in order to air-condition a room to a preset temperature, it is required that conditioned air be discharged into the room at a predetermined flow rate. In general, it is common to increase the flow rate of air which is discharged from the air discharge outlet by increasing the velocity thereof. This however creates unpleasant draft-feeling problems to the user when the velocity at which the conditioned air is discharged is increased.
With a view to coping with such problems, Japanese Patent Application Kokai Publication No. 2001-201165 discloses a technique. More specifically, in this prior art technique, an air discharge outlet shaped like a ring groove is defined around an air suction inlet so that air is discharged radially outwardly in all directions over the entire periphery of the air discharge outlet. As just described, the air discharge outlet is shaped like a ring groove to be increased in length as a whole. As a result of such arrangement, the area of the air discharge outlet is greatened, thereby making it possible to increase the flow rate of air to be discharged while making the velocity of the air as low as possible.
In the conventional indoor unit, the air discharge outlet is shaped like a circular arc. Accordingly, the flap is not allowed to swing up and down in the air discharge outlet. Therefore, the conventional indoor unit is equipped with a slide mechanism by which the flap can be shifted vertically in sliding manner.
The slide mechanism is made up of a swing link formed integrally with the flap, a lever one end of which is pin-coupled to the swing link and the other end of which is coupled to the drive shaft of a motor, a spring establishing connection between the lever and the casing, a swing shaft formed integrally with the flap and a guide groove for providing vertical guidance of the swing shaft. And, the swing shaft is guided vertically along the guide groove by the driving of the motor or by the elasticity of the spring, thereby causing the flap to move up and down. In this way, the adjustment in the flow direction of air discharged from the air discharge outlet is made.